Anil Ambani had the world at his feet in 2008 when he was named by Forbes as the world's sixth-richest person with a US$42 billion ($60.9b) bank balance.

But fast forward just over a decade, and Ambani is a man on the brink of losing it all.

The businessman and father of two is now grappling with staggering, mounting debts — and is even facing the possibility of jail time.

Ambani, 59, took over half of Reliance Group, the Indian conglomerate founded by his father Dhirubhai Ambani in 1966, following a high-profile battle with his brother Mukesh that ended with the company being split in the middle.

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Three years after their father died without a will, Anil took taking over the power generation, financial services and a telecom side of the business, while older brother Mukesh scored the oil-refining and petrochemicals side.

But earlier this month, India's Supreme Court said the company's phone unit had disobeyed a ruling to hand over payments totalling around US$77 million to the local subsidiary of supplier Ericsson.

If the company fails to cough up within a four-week deadline, Anil could spend three months behind bars.

Reliance Group has also taken hit after hit as a result of financial losses and increased competition within the telecommunications industry.

"Telecom was a tale of disaster for Anil owing to cutthroat competition, which led to industry-wide consolidation and debt overhang," Ascentius Insights principal analyst Alok Shende told Bloomberg.

Mukesh was prevented from moving into telecommunications by a non-compete clause — but when it ended in 2010, he muscled in and built Reliance Jio Infocomm Ltd, which launched a 4G wireless network across India.

As competition stepped up, Reliance Communications borrowed more and more.

But it wasn't enough to stop the company from dropping out of the number two position on the market.

Meanwhile, other branches of the company also started to falter, with shares falling in warship maker Reliance Naval & Engineering Ltd and power generator Reliance Power Ltd.

Today, Forbes estimates Anil's net worth to be just US$1.7b, representing a stunning US$40b loss over just one decade.

But while Anil is facing an uncertain future, his brother and fierce rival Mukesh is going from strength to strength.

Last year, Forbes named him as India's richest man with a net worth of US$47.3b.